The present invention relates generally to polyhydroxyl polyether compounds and polymeric resins prepared therefrom.
Polymeric resins have found wide and varied use in industry. For example, polyurethane foams are commercially used in the fields of insulation, structure reinforcement, cushioning, upholstery, electrical encapsulation, and the like. Unfortunately, polymeric resins, such as the polyurethanes, generally have very little inherent resistance to burning. In view of the extensive commercial interest in polymeric resins, there have been numerous attempts to develop an effective flame-retardant polymeric resin.
One approach to imparting flame retardancy to polymeric resins has been to incorporate a flame-retardant additive within the resin. Illustrative of such additives are: antimony oxide, tris(dibromopropyl)phosphate, chlorinated biphenyls, halogenated hydrocarbons, and the like. These additives are not chemically bonded to the polymeric backbone of the resin, but are merely physically dispersed within the resin. Consequently, such additives have the disadvantage of being especially susceptible to leaching and vaporization during aging and use of the polymeric resins.
Another approach to imparting flame retardancy to polymeric resins has been to employ a reactive flame-retardant material as an integral part of the polymeric backbone. Polyhydroxyl polyether compounds containing halogen and/or phosphorus atoms have been so used.
Such polyhydroxyl polyether compounds are a well-known class of compounds generally prepared by the polymerization of one or more monomers containing an oxirane functional group ##STR2## with a chain-initiating agent. Representative examples of polyhydroxyl polyether compounds which have found use in polymeric resins are: the trichlorobutylene oxide-based polyols described in U.S. Pat. No. 3,269,961; the trichloropropylene oxide-based polyols described in U.S. Pat. No. 3,402,169; the epichlorohydrin-based polyols described in U.S. Pat. Nos. 3,255,126, 4,072,638, 4,020,024 and Great Britain Pat. No. 1,412,384; and the trichloroethyl phosphate-based polyols described in U.S. Pat. Nos. 3,767,732 and 3,764,640.
However, for any class of flammable material, those skilled in the art have long been aware that some reactive flame-retardant materials are more effective in polymeric resins than other reactive flame-retardant materials. This is because the efficacy of any flame retardant in polymers of polymeric compositions is measured not only by the ability of the material to impart flame retardancy to the polymer, but also by the ability of the flame retardant to improve or modify, or at least not to detract from, other physical or mechanical properties of the polymer or polymeric composition.
Thus, the mere fact that a compound contains halogen and phosphorus atoms does not assure that the compound can provide usable flame retarding characteristics to the polymeric resin without substantially affecting other properties of the resin. For example, the conventional polyhydroxyl polyether compounds described above can be used to produce polymeric resins having flame-retardant properties. However, other physical properties of the polymeric resins, such as humid aging characteristics and friability are generally adversely affected. Moreover, the formulation of the polymeric resins from conventional polyhydroxyl polyether compounds is rendered more difficult because of the predominance of terminal secondary hydroxyl groups on the polymeric backbone. These secondary hydroxyl groups are well-known in the art to be much less reactive to the formulation of polymeric resins than primary hydroxyl groups.
It would therefore be desirable to provide a polyhydroxyl polyether compound which is not only capable of imparting good flame retarding characteristics to a polymeric resin, but which is also capable of insuring commercially acceptable physical properties (e.g., humid aging, friability) in the resin. Moreover, it would be advantageous if such a polyhydroxyl polyether compound had a predominance of reactive primary hydroxyl group incorporated within the polymeric backbone of the polyether.